Surprisingly Safe Cardboard Bike Helmet Gets Solid Backing

A clear version of the Kranium helmet. Photo: Courtesy of Anirudha Surabhi

It was a serious accident that sparked Anirudha Surabhi‘s senior design project at the Royal College of Art in London. He was hospitalized for several days with a concussion after a bike crash, and when he returned to school, he designed and built a new, safer, bicycle helmet out of cardboard.

Kranium, as he calls it, first started getting attention in 2010. But bike lock and helmet company Abus has since licensed the design, and plans to release in Europe a clear plastic version by year’s end, a second-generation helmet next spring, and an American version around June, says Surabhi.

“When I told my lecturers, they said that it was very risky to go through this,” he says. “But as I kept experimenting and testing, the results kept getting better and better.”

The laser-cut cardboard that replaces traditional EPS foam in the Kranium actually absorbs more impact than a regular helmet, says Surabhi. He’s got the numbers to back it up, too: Testing in China, the U.K., and Germany has shown the helmet absorbs three times as much energy as comparable foam helmets, even after multiple impacts. It’s also lighter, by 15 percent.

“Ideally they test five helmets and give you the go-ahead but since this was a unique concept they tested 50-plus helmets as they didn’t believe the results were that good,” says Surabhi. “They ultimately gave us the certification, saying that it was much better at impact absorption.”

Surabhi started with honeycomb-shaped corrugated cardboard, modeled off the impact-absorbing qualities of woodpecker cartilage, and used SolidWorks to develop a series of equations to distribute load among the lateral angles of the cardboard ribs. The result is more flexible than EPS, so it continues to absorb impact where a foam helmet would crack — hence its durability through multiple impacts.

Surabhi is far from done. Because the helmet tested so well — well enough to pass motorcycle safety standards as well — he’s building a full-face version. And yes, the cardboard is treated to be sweat- and rain-proof.